The door latch assembly disclosed herein relates generally to the task of securing a sliding door of a structure in a closed condition by the use of a latch arrangement which is releasable from the inside of the structure. Locking, securing, and latching devices for structures with openable and closeable doors (or windows) are well known. However, one field where there has been limited attention over the years relates to large sliding doors which are often found as part of farm buildings, such as barns.
The more common securing techniques for large, sliding barn doors include the use of a simple latching bar or link chain run through handles. If the property owner wants to lock the doors together in a closed condition, a shackle lock can be used to secure the link chain in a closed loop. However, these particular locking and securing techniques do not enable unlocking or unlatching from the interior of the corresponding structure. These techniques may not even enable the opening of the latching bar from the interior even when there is no corresponding locking. These design realities have two important consequences. First, if someone is still in the interior of the barn when the sliding doors are locked from the outside, that person is trapped inside. This may be one reason why a smaller “pedestrian” access door could be included as part of a barn structure. Secondly, if a person is working inside the barn and, for security reasons, wants to be locked inside, this is not an option with these conventional locking or securing techniques. Related to this desire for added security is the desire to not allow an unauthorized person to unlock the door from the outside when that door is locked from the inside.
Another consideration in the locking or securing of large, sliding barn doors is the size of the doors, most notably their height. A selected door latch would advantageously include the option of adding a second and perhaps a third latching point spaced above (or below) the primary latching location. The point is that with a door which might be in the range of twelve (12) to sixteen (16) feet wide and in the range of twelve (12) to sixteen (16) feet high, more than one latching location is desirable. However, if the second latching location is higher than eight (8) feet, most individuals will not be able to reach it. This is why a single unlocking or release action needs to be cooperatively linked to all of the other latching structures, regardless of the number or location which are assembled to the same sliding door.
An improvement to the current locking and securing techniques used for large, sliding barn doors is provided by the door latch which is disclosed herein. More specifically, the disclosed door latch structure includes an optional key lock (i.e., a key-operable lock set) and a linkage arrangement to enable opening (i.e., unlocking) from the interior of the structure as well as locking from the interior. While the focus of this disclosure is directed to large, sliding barn doors, the disclosed door latch could be used for virtually any style of door which has an inner face edge which abuts up against a door jamb or up against an inner face edge of an abutting second door.